Lately posted on Slashdot, an article written by Joel Spolsky mentioned the trouble through which Microsoft went to make each version of Windows backwards compatible. In one case, for the game Simcity, they even changed the way memory handling was done when running that application. You can find additional stories of software tricks that recent versions of Windows have to perform in order to run these bug-dependant applications on the web. After reading the story, I discussed with a couple of friends how weird this was and how Free Software completely avoids this problem.